This invention relates to a method and device for tissue resection, especially surgical treatment of the uterus or prostate.
Electrocautery has been in use for many years as a general surgical tool, such as for trans-cervical fibroid removal. The uterus is first flooded under pressure with a non-conductive sorbitol-mannitol fluid under sufficient pressure to separate the walls of the uterus and render the surgical site suitable for optical fiber observation under a procedure generally described as uterine cavity distention. During this flooding, an electrocautery surgical tool is inserted into the uterus through the cervix. Electrical current at high power settings (an alternating current about 750 KHz) is transmitted from the cutting surface of the surgical instrument to the surgical site. The cutting surface usually consists of a wire or solid shape. The transmission of current to the uterus is monopolar and completed by a conductive path to the power unit through a conductive pad applied to the patient's skin.
The electrical current is concentrated at the cutting surface. Heat generated from the resistance of tissue to the flow of electrical current is high enough to vaporize cells near the cutting surface. Thus a cut is made with very little physical resistance to the cutting action. Heat from the cut cauterizes small blood vessels so that visibility and control remain good.
In the cautery mode and during uterine cavity distention, the same electrical resistance heating is used at lower power settings to cauterize tissue and to kill selected areas. Cautery electrodes can be larger in area so as to treat broader surfaces. Cautery is used in gynecology to ablate the endometrial lining of the uterus. This procedure is often performed using a conductive roller similar in shape to a football which heats a wide swath along the inner surface of the uterus.
Electrocautery tools are compact and require a minimum of area in which to work. Since the tool only cuts when the power is turned on, they can be safely maneuvered into small areas. Electrocautery has found broad general application in the treatment of enlarged prostate glands, and in the removal of uterine fibroids.
A secondary effect of the removal of tissue, particularly in the areas of prostate reduction and fibroid removal, is that severed morsels remain in the working area and must be periodically flushed or suctioned away to preserve the required visibility necessary for surgery. The clean, well controlled action of electrocautery is now slowed by the need to remove fragments which obstruct visibility. This required removal prolongs the surgical procedure.
It is known that ultrasound can add significant value to tissue resection and ablation procedures. Using high-frequency ultrasound, anatomical landmarks and tissue features can be imaged in depth, which cannot be done by optical instruments. Depth information provides improved guidance and monitoring capabilities. It enables the surgeon to monitor the progress of tissue treatment, and thereby lessens the risk of complications. In addition, the improved visualization provided by ultrasound can help to shorten procedure times.
At the present time as for example during uterine cavity distention, it is not practical to introduce ultrasound probes without considerable complication.
To perform ultrasound measurements during electrocautery, the surgical probes for the electrocautery procedure must first be removed and thereafter, ultrasound introduced. Finally, and after such measurements, surgery can resume with reintroduction of the surgical probes. With such procedures, the surgeon has difficulty returning to the original surgical site. For this reason, ultrasound is not usually utilized for measurement of uterine wall thickness by an intrauterine transducer.